1. Technical Field of the Invention
The present invention relates to an image forming apparatus having a prewarning function for previously warning the periodic requirement of manual handling for replenishing expendable supplies as well as for exchanging parts to be exchanged, and more particularly to an image forming apparatus designed to previously give warning of the requirement for replenishment and exchange of expendable supplies and parts such as thermo-sensitive roll sheets being used in a facsimile, developer, sheets, cleaning webs, waste toner bottles used in an electrophotographic image forming apparatus and heat transfer ribbons used in a heat transfer system image forming apparatus.
2. Brief Description of the Prior Art
Heretofore, the warning of requirement for replenishment and exchange of expendable supplies and parts is given, for instance, by means of a line mark arranged on side edge of the rear end of a thermo-sensitive roll paper used in a facsimile or by an indication displayed on the operation panel of an electrophotographic copying machine and the like.
However, the warning is generally given at the final stage when such replenishment and exchange is required to be made. Thus, for a facsimile and the like which are often used at nighttime and during holidays when there is nobody in the office, the warning for replenishment and exchange is entirely useless even if such warning signal is emitted automatically and causes the machines incapable of functioning since there is no one who handles the replenishment and the exchange.
It may hence be considered to preliminarily give warning for replenishment and exchange by moving up the final stage or to arrange for giving the warning when the number of the remaining sheets is reached to predetermined number. However, when the mark provided at the rear end of a roll sheet is applied to a cut sheet originally cut in a predetermined size, the sheet specially provided with such a mark has to be prepared and set at near end portion of the sheets being used, which is quite troublesome, and moreover it can not tell the requirement of, for instance, toner replenishment and the like by such a roll sheet provided with mark, excepting the sheet replenishment.
Further, in an image forming apparatus in which various indications are made on an operation panel, such indication of warning is only one of the indications among complicated and various indications, and operators are liable to overlook the indication since such indication is not closely familiar with the operators except when the machine is operated. There leaves, therefore, problems for a facsimile and the like which are often used when there is nobody around.